Field
This disclosure relates generally to a carrier aggregation (CA) transceiver, and more specifically, to reconfiguring local oscillator dividers in the CA transceiver.
Background
A wireless device in a communication system may transmit data using a transmitter and receive data using a receiver for two-way communication. The wireless device may also support carrier aggregation, which is simultaneous operation on multiple carriers. A carrier may refer to a range of frequencies (sometimes referred to as “band”) used for communication and may be associated with certain characteristics such as system information describing operation on the carrier. Thus, it is desirable to efficiently support carrier aggregation by the wireless device.
The demand for faster data rates is increasingly driving the concurrent operations in multiple bands. For example, new bands such as B42/B43 (e.g., at 3.5 GHz) are being added to support additional spectrum for increased data rates. Thus, a carrier may perform, for example, concurrent four downlink (DL) and one uplink (UL) operations with frequencies in B3, B7, B7 intra, and B42 bands. In this example, multiple mechanisms of spurious responses due to low-noise amplifier (LNA) non-linearities (e.g., out-of-band (OOB) 2nd order intercept point (IP2)/3rd order intercept point (IP3) distortions) cause mixing of coupled voltage-controlled oscillator (VCO) signals with transmit (Tx) signals to interfere with one of the bands to cause receiver desensitization. Further, the choice of local oscillator (LO) divider ratios for different bands may result in the VCO frequencies being close to each other (for different LO frequencies), which can cause spurious responses including integrated phase noise (IPN) and error vector magnitude (EVM) degradation. To address these problems, a configuration in which the VCOs are divided into two chips to reduce the coupling issues have been proposed. However, the two-chip solution may reduce the coupling issues somewhat, but creates more problems because it will occupy more chip area and consume more current.